This invention relates generally to liquid purification, and has particular reference to a novel automatic chlorinator for swimming pools having water circulating systems.
As is well known, swimming pools require the regular addition of water soluble bacteria killing agents for safety, chlorine or compounds thereof being the agents most widely used for this purpose. Ideally, the pool water should have a residual chlorine level of from about 0.4 to about 0.6 parts per million. This level is difficult to maintain, however, because the chlorine concentration in the water is affected by many factors, the temperature, the amount of sunlight or rain and the number of bathers among them.
In many home pools, the chlorine is added manually and the residual level is tested at irregular intervals using small, manually operated test kits. This can result in a wide variation in the chlorine concentration from too little which may be unsafe to too much which may be safe but unpleasant. A number of automatic chlorinators have been developed but most of these are for municipal water systems and are too complex and expensive for home use.
An automatic chlorinator particularly designed for home pool use is disclosed in U.S. Pat. No. 3,466,450 granted Sept. 9, 1969 W. L. Goodman. This patent, which is the closest prior art known to the applicant, provides apparatus that periodically pumps a specified volume of pool water into a test chamber were a reagent is added. The reagent changes the color of the water in proportion to the amount of chlorine present. The mixture is optically tested for color and then electrically compared to a standard volume of chlorine concentration after which chlorine is added to the pool if the sample shows less chlorine concentration than the standard.